The invention relates to enabling operation of a system such as a computer that includes a plurality of ports to receive electronic devices.
In a system such as a computer, electronic devices, such as microprocessors, microcontrollers, peripheral controllers, memory devices, and the like, are coupled to ports in the system. Such ports may include sockets, connectors, receptacles, surface mount connections, or other coupling mechanisms. For example, a system configurable to operate as a multiprocessor system may have multiple ports (e.g., sockets or connectors) to receive multiple microprocessors. Because of voltage and current requirements of many high performance microprocessors, a DC-to-DC converter (also referred to as a voltage regulation module or VRM), may be coupled to supply the operating voltage to a microprocessor. Typically, one VRM may be provided for each microprocessor in a multiprocessor system, with each VRM mounted in a corresponding socket or connector or directly mounted onto a circuit board in the system. Conventionally, a microprocessor provides some indication to a VRM specifying the voltage level to be provided by the VRM to the microprocessor.
Each VRM may provide a power good signal (typically an open collector signal) to indicate if the output voltage of the VRM is within a specified voltage range. Alternatively, some other type of indication that an output voltage is valid may be provided. If not, the power good signal or other voltage valid indication from the VRM may be driven inactive to prevent system operation. In a conventional multiprocessor system, power good signals from multiple VRMs may be tied together (to provide a wired AND of the power good signals) so that system operation is disabled if any of the power good signals is inactive. If for some reason one or more of the microprocessors are removed from their sockets or connectors, the VRMs associated with those microprocessors will drive their power good signal inactive. This will disable system operation even though one or more microprocessors remain in the system.
To overcome this issue, some system manufacturers mount VRMs in sockets so that if a microprocessor is removed for some reason, the corresponding VRM may also be removed so that system operation is not disabled by the presence of an inactive power good signal. However, this may increase the complexity of and overhead associated with reconfiguring a multiprocessor system, since two parts instead of one need to be added or removed. Thus, a need exists for an improved technique and apparatus to enable system operation even though one or more devices are removed.